Shevuot 9 – A Sacrifice for God

The goat sacrifice brought on the New Moon atones for ritual impurities that never became known to the impure person. That is why this sacrifice is called "a sacrifice for God" - for God alone knows of this impurity - these are the words of Rabbi Yehudah.

Additionally, as Resh Lakish explained, God said, "This he-goat shall be an atonement for something that I did." When God created the Sun and the Moon, they were initially of the same size. The Moon complained that it was inappropriate for two rulers to rule at once, and God said, "You are right, go and make yourself smaller." The Moon then reasoned that it was unjust that it should suffer just because it raised a valid point. To placate the Moon, God promised that the Jewish people would bring a sacrifice for God's sin, as it were, on every New Moon.

Art: Man and Woman Contemplating the Moon by Caspar David Friedrich